1. Field of the Invention
The present invention relates to a device for selecting a light source for measuring the wavelength characteristics of an optical element, which modulates the optical output of a light source among a plurality of light sources which provide optical outputs of different wavelengths, respectively, by applying a modulating signal to the light source, and detects the modulated optical output to measure the wavelength characteristics of an optical element, such as an optical fiber.
2. Description of the Prior Art
The constitution of a conventional device for measuring the wavelength characteristics of an optical element such as an optical fiber is shown in FIG. 2. In FIG. 2, indicated at 7 is a measured optical element, at 11A and 11B are light sources, at 12A and 12B are connectors, at 13 is a connector and at 14 is an indicator. The light sources 11A and 11B are different from each other in the wavelength of optical output. The number of the light sources need not be limited to two, but may be increased when necessary. The connectors 12A and 12B are connected to the respective outputs of the light sources 11A and 11B, respectively. The connector 13 and the indicator 14 are connected to the input and the output of the optical element 7, respectively. The indicator 14 indicates the measured wavelength characteristics of the optical element 7. When the connector 12A is connected to the connector 13, the optical output of the light source 11A is applied to the optical element 7 and the optical output level of the optical element 7 is indicated on the indicator 14.
When the light source 11A is required to be replaced with the light source 11B to apply the optical output of the lightsource 11B to the optical element 7, the connector 12A needs to be disconnected from the connector 13 and the connector 12B needs to be connected to the connector 13. Accordingly, additional time is required for measurement. Furthermore, when the distance between the extremity of the connector 12A and that of the connector 13 and the distance between the extremity of the connector 12B and that of the connector 13 are different from each other, the connection loss is variable, and hence accurate measurement is impossible.